RELATIONSHIPS BETWEEN LANE CHANGE PERFORMANCE and OPEN- LOOP HANDLING METRICS Robert Powell Clemson University, [email protected]
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Clemson University TigerPrints All Theses Theses 1-1-2009 RELATIONSHIPS BETWEEN LANE CHANGE PERFORMANCE AND OPEN- LOOP HANDLING METRICS Robert Powell Clemson University, [email protected] Follow this and additional works at: http://tigerprints.clemson.edu/all_theses Part of the Engineering Mechanics Commons Please take our one minute survey! Recommended Citation Powell, Robert, "RELATIONSHIPS BETWEEN LANE CHANGE PERFORMANCE AND OPEN-LOOP HANDLING METRICS" (2009). All Theses. Paper 743. This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. RELATIONSHIPS BETWEEN LANE CHANGE PERFORMANCE AND OPEN-LOOP HANDLING METRICS A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Mechanical Engineering by Robert A. Powell December 2009 Accepted by: Dr. E. Harry Law, Committee Co-Chair Dr. Beshahwired Ayalew, Committee Co-Chair Dr. John Ziegert Abstract This work deals with the question of relating open-loop handling metrics to driver- in-the-loop performance (closed-loop). The goal is to allow manufacturers to reduce cost and time associated with vehicle handling development. A vehicle model was built in the CarSim environment using kinematics and compliance, geometrical, and flat track tire data. This model was then compared and validated to testing done at Michelin’s Laurens Proving Grounds using open-loop handling metrics. The open-loop tests conducted for model vali- dation were an understeer test and swept sine or random steer test. Four commonly used handling metrics (steady state yaw rate gain, yaw rate damping ratio, yaw rate bandwidth, and lateral acceleration phase lag at 1 Hz) were extracted from the frequency response functions of the swept sine test. These are the open-loop handling parameters used to draw relationships to closed-loop performance. Next, a driver model was coupled to the vehicle model in order to simulate a closed- loop maneuver. Quadratic cost functions are then introduced as a means to measure per- formance through the closed-loop ISO Double Lane Change maneuver. These quadratic metrics measure path-following ability, and the mental and physical workload of the driver. Driver model parameters were determined by weighting the quadratic cost functions to se- lect the optimum driver with the lowest total cost. In this work, highest priority was given to path-following ability in order to successfully complete the lane change without violat- ing course boundaries. Mental workload and physical workload were given lower priority because of the short length of the maneuver. As a means to change the vehicle model, three hypothetical tires are introduced. To ii have an even greater number of configurations, the vehicle model’s static weight distribution was altered. This yielded twelve different realistic vehicle configurations from which to draw conclusions. With the twelve different vehicle models considered, qualitative relationships were found between open-loop handling measures and driver-in-the-loop quadratic perfor- mance metrics. Two relationships were found to exist–when steady state yaw rate gain and yaw rate bandwidth are increased, path-following ability is enhanced. When yaw rate bandwidth is increased and lateral acceleration phase lag at 1 Hz is decreased, mental and physical workload are reduced on the driver. iii Acknowledgments I would first like to thank my advisors, Dr. E. Harry Law and Dr. Beshahwired Ayalew, for their wisdom and guidance in helping me achieve this goal. I would also like to thank Dr. John Ziegert for being a part of my committee and providing academic assistance in my graduate course work. In addition, I would like to thank Lynn Vorys for her help in the editing process of this document. A special thanks also goes to Michelin America’s Research Center and BMW for providing the funding for this project. In addition, I would like to thank Dr. Tim Rhyne and Dr. Steve Cron of Michelin and Dr. Andreas Obieglo of BMW for their continued support throughout this research. iv Dedication I would like to dedicate this thesis to my parents, David and Leslie, who have always believed in me and helped me achieve my goals. In addition, I would like to thank the rest of my family for their unwavering support throughout my educational career. To my friends and office mates, thank you for making my experience at Clemson both enjoyable and educational. A special thanks goes to Anup Khekare with whom I have had the pleasure of working on this research. v Table of Contents Abstract . ii Acknowledgments . iv Dedication . v List of Figures . ix List of Tables . xi 1 Introduction . 1 1.1 Introduction . 1 1.2 Research Motivation and Problem Statement . 2 1.3 Literature Review . 4 1.3.1 Open-Loop Handling Metrics . 4 1.3.2 Relation Between Subjective and Objective Testing . 4 1.3.3 Relationship Between Open and Closed-Loop Testing . 5 1.3.4 Driver Models . 6 2 Vehicle Models and Open-Loop Tests . 8 2.1 Introduction . 8 2.2 Vehicle Model . 9 2.3 Open-Loop Handling Tests . 10 2.3.1 Swept Sine Test . 11 vi 2.3.2 Understeer Test . 12 2.4 Validation of CarSim Model . 13 3 Closed-Loop Modeling and Metrics . 16 3.1 Introduction . 16 3.2 Driver Model A . 16 3.3 ISO Double Lane Change Course and Performance Metrics . 18 3.3.1 ISO Double Lane Change Course . 18 3.3.2 Quadratic Cost Functions . 20 3.4 Driver Parameter Selection . 22 3.5 Selection of Tire Characteristics . 29 4 Results and Discussion . 32 4.1 Introduction . 32 4.2 Open-Loop and Closed-Loop Performance with Changing Tires . 32 4.3 Open-Loop and Closed-Loop Performance Metrics with Changing Weight Distribution . 40 4.4 Qualitative Analysis Relating Open and Closed-Loop Handling Metrics . 43 5 Conclusions and Future Work . 48 5.1 Conclusions . 48 5.2 Future Work . 49 A Vehicle Model Parameters . 51 A.1 Vehicle Properties . 52 A.2 Suspension Parameters . 53 A.3 Suspension Kinematic Parameters . 54 A.4 Compliance Parameters . 58 A.5 Tire Parameters . 62 A.6 Kingpin Geometry . 63 vii B Driver Models . 64 B.1 Driver Model A . 64 B.2 Driver Model B . 67 B.3 Driver Model C . 70 C Methodology for Creating the TWEELs™ . 74 D Open and Closed-Loop Raw Data . 78 E CarSim File Formats . 81 F MATLAB Programs . 84 F.1 Model_Validation.m . 84 F.2 TWEEL_Lateral_Force.m . 93 F.3 TWEEL_Aligning_Moment.m . 105 F.4 Spider Plot Programs . 112 F.4.1 color_index.m . 112 F.4.2 isint.m . 113 F.4.3 spider.m . 114 F.5 Frequency_Response_Functions.m . 122 F.6 Lane_Change.m . 155 References . 167 viii List of Figures 1.1 Image of Generic TWEEL™ ........................... 3 2.1 Transfer Function for RWA/SWA . 10 2.2 Frequency Response Functions (LPG Test vs. CarSim Simulation) . 14 2.3 Spider Chart Comparing CarSim Simulation vs. LPG Test . 15 2.4 Understeer Test Comparing CarSim Simulation vs. LPG Test . 15 3.1 Genta driver and vehicle closed loop system . 18 3.2 ISO Lane Change Course . 20 3.3 Yerror vs. Time for each J’s Lowest Cost . 24 3.4 SWA vs. Time for each J’s Lowest Cost . 26 3.5 SWA Rate vs. Time for each J’s Lowest Cost . 27 3.6 Jtotal for OE Tire at 78 kph . 28 3.7 Cornering Stiffness versus Vertical Load for TWEELs™ . 30 3.8 Lateral Force vs. Slip Angle for OE Tire . 31 4.1 Frequency Response Functions Comparing OE Tire to TWEELs™ . 33 4.2 Spider Plot of Open-Loop Handling Metrics with Different Tires . 34 4.3 Vehicle Trajectory with OE Tire at Maximum Speed of 78 kph . 36 4.4 Vehicle Response Parameters vs. Time at 78 kph . 37 4.5 Lateral Acceleration vs. Time and Distance at 78 kph . 38 4.6 Lateral Position and Heading Angle vs. Time at 78 kph . 39 4.7 Frequency Response Functions Comparing Weight Distributions . 41 ix 4.8 Spider Plot of Open-Loop Handling Metrics for Changing Weight Distribution 42 4.9 Relating Select Open and Closed-Loop Metrics in 2-D Plots . 44 4.10 3-D Plot Comparing SS Yaw Rate Gain and Yaw Rate Bandwidth to J1 . 45 4.11 3-D Plot Comparing Lateral Accel. Phase Lag and Yaw Rate Bandwidth to J2 46 4.12 3-D Plot Comparing Lateral Accel. Phase Lag and Yaw Rate Bandwidth to J3 47 B.1 Original Genta Driver Model Block Diagram . 64 B.2 Driver Model A Simulink/CarSim Block Diagram . 66 B.3 Driver Model B Simulink/CarSim Block Diagram . 69 B.5 Driver Model C Simulink/CarSim Block Diagram . 72 B.4 Horiuchi Driver/Vehicle Closed Loop System . 73 C.1 BMW 3 Series Aligning Moment Used for Mini Cooper in CarSim . 77 E.1 Sample ERD file . 82 x List of Tables 3.1 J1 at 78 kph Normalized to Lowest Value . 24 3.2 J2 at 78 kph Normalized to Lowest Value . 25 3.3 J3 at 78 kph Normalized to Lowest Value . 25 3.4 Jtotal for OE Tire at 78 kph . 28 3.5 Driver Parameters for.